This document summarizes a research paper that investigates the effects of different group of pictures (GOP) sizes on the quality of reconstructed multiview video content transmitted over error prone channels. It finds that while larger GOP sizes allow for greater compression, they can also propagate errors spatially and temporally. It proposes a multi-layer data partitioning technique to make the multiview video bitstream more robust to errors, and implements frame copy error concealment in the decoder to replace lost information. Simulation results show the multi-layer approach performs better than standard H.264 data partitioning at higher error rates.

1. EFFECTS OF GOP ON MULTIVIEW VIDEO
CODING OVER ERROR PRONE CHANNELS
A.B Ibrahim1 and A.H Sadka2
1Department of Electronic & Computer Engineering,
Brunel University, London, United Kingdom
Abdulkareem.Ibrahim@brunel.ac.uk
Abdul.Sadka@brunel.ac.uk
ABSTRACT
In this paper, an investigation of the effects of group of pictures on H.264 multiview video
coding content over an error prone environment with varying packet loss rates is presented. We
analyse the bitrate performance for different GOP and error rates to see the effects on the
quality of the reconstructed multiview video. However, by analysing the multiview video content
it is possible to identify an optimum GOP size depending on the type of application used. A
comparison is demonstrated for the performances between widely known H.264 data
partitioning error resilience technique and multi-layer data partitioning technique with different
error rates and GOP in terms of their perceived quality. Our simulation results turned out that
Multi-layer data partitioning technique shows a better performance at higher error rates with
different GOP. Further experiments in this work have shown the effects of GOP in terms of
visual quality and bitrate for different multiview video sequences.
KEYWORDS
Multiview Video Coding, Group of Pictures, Error rates, Bitrate, and Video quality.
1. INTRODUCTION
Three-dimensional technology widely known as 3D technology has transformed many fields of
discipline such as entertainment, communications, medicine and many more. 3D can be perceived
in a number of different ways. We shall restrict our understanding to just multiview video coding
in this paper. Generally, the main concept of video coding is to exploit the statistical correlation
between consecutive frames. The MVC extension of the H.264/AVC exploits these similarities
between frames, simplifies the decoding process, and advances new features that are specific to
multiview video coding [1] . Multiview video coding has emerged as advancement in video
coding technology. The multiview video coding system enables efficient encoding of sequences
that are captured from different cameras at different locations at the same time. The H.264 MVC
codec takes as an input several synchronized bitstream that are captured from several different
cameras and generate a single bitstream as an output for storage or transmission [2]. The work in
[3] gives a detailed overview of the MVC standard. The structure of MVC is defined by a concept
known as matrix of pictures (MOP). In this technique, each row consists of a group of pictures
(GOP) normally captured by the base view and each column represents the time domain of the
video.
David C. Wyld et al. (Eds) : SAI, CDKP, ICAITA, NeCoM, SEAS, CMCA, ASUC, Signal - 2014
pp. 135–150, 2014. © CS & IT-CSCP 2014 DOI : 10.5121/csit.2014.41114

2. 136 Computer Science & Information Technology (CS & IT)
2. BACKGROUND
The H.264/AVC international standard [4] has specifies a coding standard of video data. H264
defines three picture types namely I-frame, P-frame, and B-frame. In a standard reference
multiview video encoder all the pictures in a multiview video are encoded with a fixed GOP
length depending on the settings and applications. The arrangement of these three picture types in
a sequence is distributed statistically within the group-of pictures. The special type of I-frame at
the beginning of a sequence also known as an IDR frame serves as an entry point to facilitate
random seeking or switching between channels. This can further be used in providing coding
robustness to transmission errors [5] which are only coded with moderate compression to reduce
the spatial redundancies in the multiview video sequence. I frames are generally larger than P and
B frames which means the less you have the longer the GOP size and the more compression you
can get. But in multiview video content transmission especially in error prone channels, very long
GOP can have an adverse effect of propagating error spatially, temporally and in interview
direction. P frames are coded in an efficient way through the concept of motion compensation
from either a past I or P frame which are mostly used as a reference to predict further. B frames
have a very high compression ratio which requires the presence of both a past and future
reference pictures for motion compensation.
Figure 1. MVC prediction structure with GOP size of 8 [6].
Fig. 1 depicts a multiview video coding prediction structure with GOP size of 8 where I, P, and B
represents the encoding of pictures in intra mode, predicted mode and bi-predicted mode
respectively. The compressed multiview video data is highly sensitive to noise and information is
loss due to the removal of statistical and subjective redundancy in the video by the compression
scheme [7]. H.264/AVC employs variable length coding (VLC) in order to achieve higher
compression gain. This type of predictive coding technique makes the video data highly sensitive
to bit errors, and the effects of errors on the perceptual video quality can be quite severe. Thus, it
is necessary to provide an effect technique and configuration settings that can make the MVV
bitstream more robust to transmission error and to improve the visual quality of the reconstructed
multiview video [8]. The effectiveness of H.264/AVC coding depends on many coding
parameters one of which is GOP size and its internal organization [9]. Most standard reference
H.264 codecs use a fixed size for the GOP to encode video sequences. The GOP size can have
different values as specified by the standard, however, once a given size is chosen, it becomes
applicable to the entire coding process and the corresponding standard decoder can be able to sort
out the positioning of these frames during decoding process.

3. Computer Science & Information Technology (CS & IT) 137
2.1. Concept of Data Partitioning in H.264/AVC
The H.264/MPEG-4 AVC standard is established to represent complete video information in a
much lower level called the slice. A H.264 video slice consists of an arbitrary integer number of
successive macroblocks that represent different types of video data [10]. Slice header conveys
information that is common to all the MBs in the slice such as the slice types which determine
which MBs types are allowed, and frame number that the slice corresponds to, reference picture
settings and default quantization parameter. The slice data section consists of a series of MBs that
make a slice.
Figure 2. H.264/AVC Slice layout with data partitioning
A0 A1 A2 B0 B1 B2 C0 C1 C2
Figure 3. Multi-Layer data partitioning technique
In DP technique, MV and the residual information are separated by a boundary marker which is a
uniquely decodable codeword. The codeword indicates the end of header information in a slice
and the beginning of residual information [11]. Recent study on the concept of DP can be found
in [12]. Data partition, nonetheless, creates more than one bit string (partitions) in every slice, and
rearrange all symbols of a slice into a separate partition that have a close semantic relationship
with each other Fig. 3. In H.264/AVC, when data partition is enabled, each slice of the coded
bitstream is divided into three separate partitions with each of the partitions being from either
type A, type B or type C partitions. Type A partition consists of header information, Quantization
parameter (QP), Macroblock type, reference indices and motion vectors. The intra partition also
called type B consists of the Discrete Cosine Transform (DCT) intra coded coefficients and the
inter partitions also known as type C partitions contain DCT coefficients of motion compensated
Inter-frame coded MBs. Type C partition in many cases is the biggest partition of a coded slice
and yet the least sensitive to error because its information does not synchronise the encoder and
the decoder [13]. Each partition is placed in a separate Network Abstraction Layer (NAL) unit
and may be transmitted separately over a network. The use of both Types B and C will require a
type A partition and not vice-versa.
2.2. Previous Work
The implementation of data partitioning technique for MVC is presented in [14]. A video slice
without any ER mechanism may be affected by transmission errors that can lead to the loss of the
entire information within the slice. Implementation of error resilience techniques such as data
partitioning in the JMVC reference software is necessary because there is no provision for any ER
technique in the MVC in the reference software. Therefore, in order to analyse the performance of
MVC in error-prone networks, implementation of a valid error resilience technique such as data
partitioning as shown in Fig. 2 is employed and implemented in the JMVC 8.5 reference software.

4. 138 Computer Science & Information Technology (CS & IT)
From the H.264 data partitioning technique, a video slice can be recovered when either partitions
B or C, or both, are affected by transmission errors as long as the partition A is not affected or lost
as a result of losing the header and motion information contained therein. It has been observed
that the performance of H.264/AVC data partitioning technique in MVC is not too encouraging
and further error performance improvements can be made through the introduction of the
proposed multi-layer data partitioning technique depicted in Fig.3.
Figure 4. Flow diagram of the Multi-Layer DP technique
2.3. Multi-Layer Data Partitioning Technique
In an attempt to make the MVV bitstream more error resilient to the transmission errors in an
error prone network, we propose a technique that can create two-layer of partitioning for each
slice in the multiview video bitstream. The general concept of the technique is illustrated in
Fig.4.The assembled multiview video bitstream is parsed in the developed Multi-Layer DP
application for increased robustness against the transmission errors before transmitting over the
wireless network. The partitioned bitstream is received by the modified JMVC reference decoder
in order to decode and reconstruct the multiview video bitstream for viewing at the display.
Multi-Layer DP adopts a mechanism that restructures a video slice as shown in Fig. 3. A0
partition consists of the header information of frame 0 from view 0, and A1 partition consists of
the header and motion information of frame 1 from view 1 and A2 partition consists of the header
and motion information of frame 2 from view 2. B0 consists of the residual information of intra
coded MBs of frame 0, B1 consists of the residual of intra coded MBs in frame 1 and B2 consists
of the residual of intra coded MBs of frame 2 and C0 is an empty partition, C1 consists of
residuals of inter coded MBs and C2 consists of the residual of inter coded MBs of frame 2 and in
that sequence it continues till nth view and nth last slice of the multiview bitstream.
Note that, partition C0 is empty because there is no residual information of inter-coded MB’s in
frame 0 which is an intra-coded frame. I-frames are self-referential and do not require any sort of
information from other frames to be predicted, so it consists of only intra coded MBs. The H.264
compliant encoder needs not to send empty partitions to the decoder because a standard H.264
decoder will assume missing partitions are empty partitions and are designed to handle the
multiview bitstream accordingly [15]. During the decoding process of the MLDP bitstream, the
decoder is modified to cope with the lost video data due to errors in the wireless channel.
The effects of displaying a frame reconstructed from a corrupted data can adversely degrade
visual perception by introducing artefacts. In order to support the MLDP technique more
effectively and to minimise the effects of channel errors in the multiview video bitstream, a
simple and commonly known error concealment technique is employed and developed in the
JMVC 8.5 reference decoder. Lost data in the bitstream can be concealed by copying the
information from previously received error free slices. Frames that are generated by copying
related video data in order to replace lost information are not always perceptually noticeable by a
viewer which is an advantage of this technique especially in low-activity scenes [16]. In our

5. Computer Science & Information Technology (CS & IT) 139
approach, we are able to support multi-layer data partitioning technique with improved quality by
employing frame copy error concealment which works fairly well with MVC and is simple to
implement; however, there are more complex techniques that use an elaborate approach to exploit
the redundancy within the video frame in order to come up with a more efficient estimate of the
lost data [3].
Time first coding Fig. 5 is a MVV bitstream format representation that allows all views to be
encoded and then assembled in a time domain for suitable transmission. The decoder on the other
side can receive and reorder the bitstream in the right decoding order, which can allow it to
decode all the pictures in different views in the same time domain and display the videos in the
correct order.
Time first coding supports the implementation of frame copy error concealment in MVC. That is
because of the display nature of all the frames across the views in the same time domain, which
makes it easier to conceal missing pictures from previously received pictures in the reference list.
Figure 5. Time first coding [1].
Currently, the MVC reference decoder only accepts H.264 compliant bitstream and does not
support the decoding of erroneous coded video sequence. In order to be able to decode the
corrupted multiview video bitstream, the H.264/AVC frame copy error concealment technique is
implemented in the JMVC reference decoder to adapt and cope with the losses within the
bitstream. Frame copy error concealment technique is simple and usually quite effective in a
video content where the motion is not large [17]. In Addition, the JMVC 8.5 reference codec has
two types of reference frame lists that is also part of the standard and can be used to support
frame copy error concealment in MVC. The first list is a reference list 0 which can be used for
both P and B frames while reference list 1 is only applicable for B-frames. The main difference
between the two reference lists is that list 0 utilizes the temporally earlier key frames (I or P)
within the GOP in a sequence while in the case of the reference picture list 1; it utilizes
temporally closer reference frames which can be a B frame [18]. Conceptually, reference list 1
can ensure smoother pictures because the frame to be copied is nearer to the picture to be
reconstructed.
2.4. Proposed decoding scheme
H.264/AVC Frame copy error concealment technique is implemented in the JMVC reference
decoder and further modified to decode the Multi-layer DP bitstream with losses as earlier
discussed in the previous section. The technique is optimized to reconstruct all the views
successfully from the multiview coded bitstream with a higher level of quality in conformance
with the standard [19].
Part of the reasons and motivation to adopt frame copy error concealment technique in our work
is its convenience to replace missing pictures especially in the case of packet loss network.

6. 140 Computer Science & Information Technology (CS & IT)
The flowchart in Fig. 6 illustrates the implementation of frame copy error concealment technique.
The technique can conceal lost information in the MVV bitstream with an improved perceptual
quality based on some experimental results presented later in the paper.
When the ML data partitioned bitstream is transmitted over the network and is received, it is first
buffered and rescheduled back to the standard H.264 DP format for processing. Note that, the
multi-layer data partitioning technique employed during source coding is only to make the
multiview video bitstream more resilient to channel errors during transmission or streaming over
the simulated wireless network. After successfully delivering the bitstream across the network,
then the received bitstream is rescheduled back to the standard H.264 data partitioned format for
decoding.
The decoder checks if the buffer is full then all the frames are sent directly for decoding. Also,
note that all the slices are partitioned into three different partitions encapsulated into VCL NAL
units of DP A, DP B and DP C respectively. The decoding of these types of slices is such that the
loss of one partition might make another partition useless. In order to correctly decode partitions
B and C, it is important for the H.264 standard compliant decoder to know how each and every
macroblock is predicted within a slice. This information is stored in partition A as part of header
information. Therefore, loss of partition A can render partitions B and C useless even when
correctly received and decoded. Partition A does not necessarily require the information from
partition B and C to be correctly decoded.
Figure 6. Decoding scheme for erroneous MVV bitstream

7. Computer Science & Information Technology (CS & IT) 141
So, if only partition A is correctly received then the error concealment algorithm can utilize useful
information such as motion vectors to reconstruct the slice. However, if partition A is lost
regardless of whether partition B or/and C is/are received. The frame copy error concealment is
invoked by the decoder to replace the missing picture information by a previously received
picture in the reference list. If the buffer is empty, then the NAL units are read from the MVV
bitstream and the decoder determines whether it is a non-VCL NAL unit or VCL NAL unit? All
non-VCL NAL units are sent directly for decoding while the VLC NAL units are all read until the
next prefix NAL unit is detected and are rescheduled to the H.264 format before decoding. The
whole process is restarted again through a looping system.
3. SIMULATION
To show the performance of 3D MVV bitstream over a wireless error-prone network, a number of
coding and transmission experiments and simulations are performed in both JMVC 8.5 reference
software and OPNET 16.1 network simulator [20]. This section describes the conditions used in
the experimental setup.
3.1. Video Encoder Settings
Different MVV test sequences were used in the experiment and simulations such as Ballroom,
Exit, and Vassar. Frame size of 640X480, Frame rate = 25 f/s, Number of Frames per view = 250,
and Quantization parameter (QP) was carefully selected and set to 31 and an intra-coded frame
was inserted every 13th frame in order to limit the temporal error propagation. The JMVC 8.5
reference software and simulations were configured as in [18]. Symbol mode is set on Content
Adaptive Variable Length Coding (CAVLC) to support the DP in the extended profile, also one
slice per NAL unit is considered as part of the H.264/AVC network friendly design [21]. Three
views of each of the MVV test sequences were considered to generate the MVV bitstream used
for transmission over the simulated network.
3.2 Transmission Simulation Setup
This section describes some of the necessary conditions and parameters used in the network
simulation setup. The robustness of MLDP against channel errors is demonstrated by examining
the performance of the MVV bitstream transmitted over a WIMAX simulated channel under
varying channel conditions and error rates. Multiple Subscriber Stations (SS) that represents
source and destination nodes are configured to share a common Base Station that is connected to
the core network through an IP backbone. The WIMAX model in OPNET does not have a direct
approach to upload and introduce errors in an MVV bitstream file. Trace file of the MVV
bitstream need to be generated first and simulated across the network. Transmission error
distribution formats have been developed for different error rates in the model. The network
simulation methodology is similar to the work in [22]. The MVV bitstream is decoded and
evaluated after being received by the application client for different error rates in the network.
The objective quality of the reconstructed videos is measured and analysed in terms of Peak
Signal to Noise Ratio (PSNR) which is a widely known objective metric used to measure the
reconstructed video quality [23].
3.3. Experimental Results and Analysis
This section describes the performance evaluation and results of the effects of GOP size on
multiview video bitstream over the wireless network. The values of GOP sizes used in the
experiments are 4, 8, 12, and 16 respectively. Also, the error rates used are 0%, 1%, 5%, 10%,

8. 142 Computer Science & Information Technology (CS & IT)
15%, and 20% respectively. For every GOP size and error rate considered, ten different
simulations are conducted, and the average results are generated. The perceptual quality of each
reconstructed view is measured in terms of peak signal to noise ratio (PSNR) for all the different
simulations and error rates used in the experiment. Ballroom sequence experimental values for
perceptual quality are generated in table 1 for different loss rates and GOP sizes
.
In Fig. 6, we evaluate both the H.264 DP and the multi-layer DP method for different error rates
and GOP size. We have observed for different runs in our simulations that high error rate (20%)
multi-layer DP has a better and improved quality performance than the H.264 DP technique in
many instances. Note that, video coding works either as fixed quality and variable bitrate and
vice-versa.
In this experiment for various quality levels with GOP of 4, 8, 12 and 16, corresponding constant
bitrates of 1909.69kb/s, 1619.76kb/s, 1527.94kb/s, and 1374.75kb/s are respectively reported for
ballroom test sequence Fig. 7.
In Fig. 8 and 9, the results of the experiment have revealed that a small number of GOP size
means more I frames. This can have a tendency to consume more of bits because of the frequent
occurrence of intra frames within the GOP. However, having more I-frames increases the
multiview bitstream size. It can have a tendency of reducing the efficiency of the multiview video
coding. Different applications can have different GOP requirements such as real time and offline
applications each having a different latency or delay requirement [24].
In Fig. 10, the results obtained illustrate that lower GOP size can give a better perceptual quality
in the multiview video. This is because low GOP means more intra frames within the GOP with
less prediction error which can result in a higher video quality. In video communications over-error
prone environment, trade-off between perceptual quality and bitrate consumption is
important and necessary [25]. In most cases, applications requiring a high level of quality in an
error-prone network can have a higher bitrate in order to make the MVV bitstream more resilient
to channel noise and that result in visual quality improvement. [26]
3.3.1. Objective and Subjective analysis
Table 1. Numerical simulation results
Ballroom GOP4
Ballroom GOP8
PLR (%) H264 DP (dB) H264 ML (dB) H264 DP (dB) H264 ML(dB)
0 35.45 35.45 35.16 35.16
1 34.53 34.93 34.67 34.72
5 28.54 28.90 30.28 27.97
10 24.73 24.37 26.82 24.96
15 21.04 22.93 21.35 21.90
20 18.65 20.04 18.09 19.04
Ballroom GOP 12 Ballroom GOP 16
PLR (%) H264 DP ( (dB) H264 ML (dB) H264 DP ( (dB) H264 ML(dB)
0 34.99 34.99 34.83 34.83
1 34.74 32.83 34.38 33.41
5 30.42 30.10 30.42 31.82
10 24.24 24.22 24.61 25.59

9. Computer Science & Information Technology (CS & IT) 143
15 20.94 21.63 19.23 22.52
20 18.23 20.09 16.01 19.17
Ballroom
Figure 6. Quality evaluation for different error rates and GOP sizes
Ballroom
Figure 7. Bitrate performance for different GOP sizes
40
35
30
25
20
15
0 1 5 10 15 20
PSNR (dB)
Packet Loss Rate (%)
standard GOP4 modified GOP4 standard GOP8 modified GOP8
standard GOP12 modified GOP12 standard GOP16 modified GOP16
4 8 12 16
2000
1900
1800
1700
1600
1500
1400
1300
1200
Bitrate (Kb/s)
unpartitioned 1897.568 1607.6144 1515.9464 1362.6061
H264 DP 1909.69 1619.76 1527.94 1374.75
H264 ML 1909.69 1619.76 1527.94 1374.75
GOP size
unpartitioned H264 DP H264 ML

10. 144 Computer Science & Information Technology (CS & IT)
4 8 12 16
2500
2000
1500
1000
500
Vassar 759.05 657.69 691.68 572.54
Exit 834.36 722.12 620.44 535.23
Ballroom 1909.69 1619.76 1527.94 1374.75
Figure 8. Bitrate performance for different GOP and test sequences
Figure 9. Quality and bitrate evaluation for different test sequences
0
Bitrate (kb/s)
GOP size
Vassar Exit Ballroom
38
37.5
37
36.5
36
35.5
35
34.5
0 500 1000 1500 2000 2500
PSNR (dB)
Bitrate (Kb/s)
Ballroom Exit Vassar

11. Computer Science & Information Technology (CS & IT) 145
4 8 12 16
38
37.5
37
36.5
36
35.5
35
34.5
34
33.5
33
Ballroom 35.45 35.16 34.99 34.83
Exit 37.58 37.36 37.25 37.11
Vassar 35.37 35.3 35.32 35.27
GOP size
Ballroom Exit Vassar
Figure 10. Quality evaluation for different GOP sizes and test sequences
PSNR (dB)
The subjective results are presented for ballroom sequence for different views in Figures 11-13.
In the demonstration, frame 121 is chosen from each view at 20% loss rate and a GOP of 16. It
can be observed that Multi-Layer DP technique can improve the perceptual quality performance
than H.264 DP technique. The greyscale effect in Multi-layer DP technique is completely
removed. We can observe closely in the Multi-layer DP that these frames are not reconstructed
with the best quality when compared with the original frames. This is because of the high error
rate used in the network simulations and the inability of the frame copy error concealment to
recover high losses. At such error rate of 20% and GOP of 16, the multi-layer DP technique could
recover most of the lost video information with improved quality compared to H264 DP
technique at the same error rate and GOP size. It is important to analyse the effects of error
propagation within a GOP of the multi-layer data partitioned bitstream. In hierarchical GOP like
the one in multiview video coding, the reference decoder uses the I-frame in the base view and
the anchor frames in the non-base view either directly or indirectly as reference frames for all
other frames with the GOP. If an error occurs in the I-frame of view 1, it can result to artefacts
that can continue to propagate throughout the GOP structure. The effect can be experienced in
both temporal and interview manner until the next random access point. At this point, the decoder
refreshes with the next intra coded frame in view 1 or the anchor frames in either view 2 and 3. It
has been noticed that losses within the I-frame that does not affect the header information such as
intra coded MBs coefficient can also propagate errors throughout the GOP. P-frames are coded
using motion compensation prediction from previous reference frames. From Fig. 1, anchor
frame such as the one in view 3 is forward predicted from the I-frame in view 1, subsequent
prediction of other non-anchor frames in both view 3 and view 2 takes reference from their
preceding P-frame. Any form of loss in this frame can further propagate error through the
remainder of the GOP until the next refresh frame is received within the multi-layer partitioned
bitstream. It can be highlighted that the impact of P-frame or anchor frame of view 3 can be
almost as significant as losing an I-frame due many of interdependencies from other frames. Due
to the hierarchical nature of MVC bitstream, anchor frame in view 2 that is interview predicted
from view 1 and view 3 is used to predict other non-anchor frames temporally within the GOP. So
the effect of error is limited to view 2 only and less severe than I and P-frames in the multiview
video bitstream.

12. 146 Computer Science & Information Technology (CS & IT)
Original
H264 DP
ML DP
Figure 11. Subjective quality comparison of frame 121 of view 0
at 20% error rate and GOP=16 for Ballroom sequence.

13. Computer Science & Information Technology (CS & IT) 147
Original
H264 DP
ML DP
Figure 12. Subjective quality comparison of frame 121 of view 1
at 20% error rate and GOP=16 for Ballroom sequence.

14. 148 Computer Science & Information Technology (CS & IT)
Original
H264 DP
ML DP
Figure 13. Subjective quality comparison of frame 121 of view 2
at 20% error rate and GOP=16 for Ballroom sequence.

15. Computer Science & Information Technology (CS & IT) 149
4. CONCLUSIONS
The GOP within a video sequence is one of the key coding parameters that determine the video
quality perception of the viewer, more importantly, the GOP size and the motion within the
sequence. Large GOP size improves the compression efficiency, which can allow more or higher
video content to be transmitted for a given bitrate. However, the effects of error propagation or
artefacts due to transmission error in an IP network might be longer. It is necessary to wisely
decide what GOP structure and size to support any application such as streaming or transmitting
videos. The work in this paper examines the effect of GOP size on erroneous multi-layer data
partition bitstream when transmitted over error-prone networks. However, the study in this paper
focuses and illustrates the performance of the two algorithms for worst case scenario. Two
different techniques namely H264 DP and multi-layer DP are used to demonstrate this effect. Our
experimental results illustrate that the Multi-Layer DP technique can improve the visual
perception of reconstructed videos for higher error rates within allowable compression efficiency
and bitrate. From the results obtained, we can assume and suggest that multi-layer DP technique
can suitably be utilized for delivering multiview video content over bandwidth constraint and
high error rate channel at a GOP size of 16. Please note that the work in this paper is not claiming
to achieve a remarkable visual quality. We are proposing based on simulated results a different
approach that can apparently improve the visual quality of multiview video in a very high error
rate channel. Part of our future work is to optimize the multi-layer data partitioning technique by
implementing error protection technique. The idea is to protect the multiview data from the high
error rate in the channel. The decoder error concealment algorithm is going to be extended to
employ the hybrid method that can fully exploit the redundancies between macroblocks in both
spatial/temporal and interview direction. We anticipate that from our current findings and results,
more and better visual quality can be achieved when these techniques are implemented while
considering the cost of bit rate and coding efficiency.
ACKNOWLEDGEMENTS
The authors would like to thank the Petroleum Technology Trust Fund (PTDF) for the research
sponsorship.
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Abdulkareem Bebeji Ibrahim received the B.ENG. degree in electrical engineering
from Bayero University Kano, Nigeria, in 2005, and the MSc. degree in satellite
communication and space systems from the University of Sussex, Brighton, United
Kingdom, in 2011. He is currently pursuing his PhD. degree in electronic and computer
engineering at Brunel University London. His current research interests include error
resilience and concealment for 3D multiview video coding and perceptual 3D multiview
video quality.
Professor Sadka received the Ph.D. degree in electrical and electronic engineering from
Surrey University, Surrey, UK, in 1997. He has nearly 20 years’ worth of academic
experience and a long track record of scientific leadership in the area of Video Processing
and Communications. He is the former Head of the Department of Electronic and
Computer Engineering at Brunel University and the Founding Director for the Centre for
Media Communications Research.
He has over 200 publications in refereed journals and conferences 3 patents and a
specialised book entitled "Compressed Video Communications" published by Wiley in 2002. To date,
he has managed to attract circa £4M worth of research grants and contracts and has graduated 20 PhD
students. He is widely supported by industry and runs his consultancy company VIDCOM. He is a fellow
of the IET, a fellow of the HEA and a senior member of the IEEE.